One study, published in 2008 by a group of Army researchers in the New England Journal of Medicine, even downplayed the role of mild TBI, suggesting that people should use the word "concussion" rather than "mild traumatic brain injury" to avoid perpetuating the belief they are suffering from a long-term injury.

Medical groups want to get the message "to the athletes, their parents and their coaches that a concussion is not just a ding, or getting your bell rung, but it is an injury to the brain," said Dr. Mark Halstead of Washington University, who co-authored an earlier concussion report for the American Academy of Pediatrics.